[FEATURE] Show the updated_at timestamp of the configuration value

[lewisvoncken]

There is an updated_at timestamp available for every configuration value saved in the database.

This will be shown when there is a value available.

[erikhansen]

@ericthehacker Are you still maintaining this repo? @lewisvoncken reached out to me on the Magento Community Engineering Slack Workspace, asking this:

How are you doing? I was wondering if you are still maintaining the Config Shope Hints module? there are several unmerged pull requests